Process for preparing nonconjugated diolefins

ABSTRACT

Process for codimerizing conjugated diolefins and lower Alpha olefins to nonconjugated diolefins. The catalyst system employed is a mixture of (1) an iron compound, (2) a reducing agent which is an organo aluminum compound, and (3) a ligand described as a bidentate nitrogen compound.

United States Patent Bryson Sept. 9, 1975 1 PROCESS FOR PREPARING 3,565,875 2/1971 Bozik ct a] 252/431 N NONCONJUGATED DIOLEFINS 3,669,949 6/1972 Y00.,. 1 260/680 B 3,677,968 7/1972 Bozik ct alv. 252/431 N Inventor: Jay G. Bryson, Tallm dg Ohio 3,836,602 9/1974 Widcman 260/673 [73] Assignee: The Goodyear Tire & Rubber Company, Akron, Ohio Primary Examiner-Paul M. Coughlan, Jr. Attorney, Agent, or FirmF. W. Brunner; J. Y. [22] Filed. Mar. 18, 1974 clowney; R. A Thompson 21 App]. N0.: 452,241 v [57] ABSTRACT 52 U.S. Cl. 260 680 B; 252 431 N E 1 Int Cl 2 C07/C 3/21 Process for codimerizing con ugated d1olefins and [58] Fie'ld 252/431 N lower a-olefins to nonconjugated diolefins. The catalyst system employed is a mixture of (1) an iron com- N. pound, (2) a reducing agent which is an orguno alumi- [56] References uted num compound, and (3) a ligand described as a biden- UNITED STATES PATENTS tate nitrogen Compound 7 144L627 4/1969 Schneider 260/680 B 3539,6152 11/1970 Schneider 260/680 B 6 Claims, No Drawings PROCESS FOR PREPARING NONCONJUCATED DIOLEFINS This invention relates to the codimerization of hydrocarbons. More specifically, it relates to an improved process for the production of nonconjugated diolefins from the codimerization of conjugated diolefins with lower a-olefins.

it is known that lower oz-olefins and conjugated diolefins can be catalytically converted into codimers. These codimers are acyclic in nature and can take several forms. Certain nonconjugated diolefins such as 1,4 hexadienes are useful as comonomers in the preparation of terpolymers, and being one of the products that can result from the codimerization of certain conjugated diolefins and lower a-olefins, it is desirable to obtain as high a yield to the 1,4-hexadiene as possible.

It is known that certain iron-containing catalysts are useful in the codimerization oflower a-olefins and conjugated diolefins. These prior art processes which have been reported, for instance, use a catalyst system comprising a mixture of 1) an iron salt or complex. (2) a reducing agent, such as triethylaluminum, and (3) a ligand or other compound which has been determined to promote the desired product.

However, it has been observed that these prior art processes, while a substantial amount of the starting materials are converted to codimer, the selectivity to the desired product, namely the conjugated diolefins, is not very good. For instance, in prior art processes for codimerization oflower oz-olefins and conjugated diolefins, the yield of the desired product is usually less than 60 percent.

It has been discovered that when certain changes in the catalyst ligand are employed, there is a considerable improvement in the rate of conversion of the conjugated diolefin to the codimer and some improvement in the selectivity to the nonconjugated diolcfin material.

Accordingly. the invention is a process for the conversion of conjugated diolefins selected from the group consisting of isoprene, piperylene, Z-ethyl-l ,3- butadiene, Z-phenyll ,3-butadiene, Z-methyll ,3- pentadiene and 3-methyl-l,3-pentadiene, with lower a-olefins to nonconjugated diolefins. Thus, the invention comprises contacting said conjugated diolefins and lower oz-olefins with a ternary catalyst system com prisng I) an iron compound selected from the group consisting of iron salts and iron complexes, (2) an organoaluminum compound, wherein the improvement comprises adding (3) a ligand which is characterized as a bidentate nitrogen compound in which the moiety occurs.

The lower a-olefin hydrocarbons which can be utilized in this invention are ethylene, propylene and lbutene. The preferred lower oz-olefin is ethylene.

A more preferred group of monomers for codimerization would be isoprene codimcrized with ethylene.

The second component of the catalyst system are reducing agents consisting of at least one member of the group consisting of organoaluminum compounds. Representative but not all-inclusive of suitable organoaluminum compounds are triethyl aluminum. triisobutyl aluminum, lithium tetraethyllaluminate, diethyl aluminum ethoxide and the like. Trialkylaluminums such as triethylaluminum are the preferred organoaluminum are the preferred organoaluminum compounds for use with this invention.

The iron compounds useful in the practice of this invention are preferably the iron salts of carboxylic acids containing from 2 to 40 carbon atoms, or the iron complexes of such agents as 1,3-diketones. Representative but by no means exhaustive of the iron salts of such carboxylic acids include iron acetate, iron propionate, iron isobutyrate, iron n-pentanoate, iron 3-methyl butyrate, iron octanoate and various other iron salts of other carboxylic acids containing from 2 to 40 carbon atoms.

Representative of the iron complexes are iron 2,3- pentanedionate (commonly called iron acetylacetonate), iron 3-methyl-2,4-pentanedionate, iron l-ethoxyl ,3-butanedionate, iron 1 ,3-diethoxyl ,3- propanedionate, iron-l ,3diphenyll ,3- propanedionate, iron l-cyclohexyL1,3-butanedionate and other iron complexes of l,3-diketones.

Also useful in this invention as an iron salt are the iron salts of alkyl substituted naphthenic carboxylic acids and the iron soaps or the soap called iron drier compounds. The iron salts of individual naphthenic acids are rarely found because the naphthenic acids are usually complex mixtures with their common derivatives being cyclopentane, cyclohexane. cycloheptane, and the higher molecular weight alkyl substituted analogs.

The cyclic soaps useful in this invention are usually iron in combination with fatty acids such as stearic resin (resinates) and tall oil (tallate).

Of all the compounds useful as the iron salt or iron complex in this invention, iron octanoate and iron acetylacetonate are preferred.

it has been discovered that certain of the catalyst systems utilized in this invention have a more powerful directing tendency to one isomeric form than the other. For instance, if isoprene and ethylene are codimcrized, it is possible that the product could be a 50/50 mixture or a 4-methyl-l,4-hexadiene and a 5-methyl-l ,4- hexadiene. Sometimes it is desirous to have more of one isomer than the other for final end use. It has been discovered that certain catalyst compositions give catalysts which cause the codimerization of ethylene and isoprene to give predominantly S-methyl-l ,4- hexadiene. Such compositions are illustrated by Examples l4 and 15. Certain other catalyst compositions, such as Examples 1 and 10 cause the codimerization of ethylene and isoprene to give predominantly 4-methyl- 1,4-hexadiene, in higher selectivity and with greater catalyst activity than prior art iron-based catalysts.

The third component of the ternary catalyst system of this invention consists of a nitrogen bidentate ligand. Ligand is defined as an iron or molecule bound to and considered bonded to a metal atom or ion. Bidentate means having two positions through which covalent or coordinate bonds with the metal may be formed. The ligands useful in this invention are certain bidentate nitrogen compounds. These ligands are believed to direct the reaction toward codimerization wherein the codimer goes mainly to nonconjugated diolefins. The class of ligands which is employed in the present invention are those ligands responding to the formulas:

a. The compounds of the formula where R and R can be at least one hydrogen or methyl, R and R can be at least one hydrogen, alkyl, alkoxy, and/or dialkylamino group (where the alkyl or alkoxy contain from 1 to 4 carbons), and where R and R can be hydrogen or methyl.

b. The compounds of the formula where R can be hydrogen, or alkyl (1-4 carbons), R

and R" can be at least one hydrogen, alkyl, alkoxy, and- /or dialkylamino group (where the alkyl or alkoxy contain from 1 to 4 carbons) and where R can be hydrogen or methyl.

c. The compounds of the formula where R, R and R can be at least one hydrogen, alkyl, alkoxy and/or dialkylamino (where the alkyls or alkoxy contain from 1 to 4 carbons) and R can be hydrogen or alkyl 1-4 carbons).

Representative of the compounds which can be uti lized in this invention, which correspond to the above formulas are: glyoxal-bis-(2,6-dimethylanil), biacetylbis( 2,6-dimethylanil glyoxal-bis-( 4-methylanil), biacetyl-bis( 4-methylani1 glyoxal-bis-( Z-methylanil), biacetyl-bis-(2methylanil), glyoxal-bisanil, biacetylbisanil, glyoxal-bis(4-ethoxyanil), biacetyl-bis-(4- ethoxyanil), glyoxal-bis-( 3-methoxyanil), biacetyl-bis- (3-methoxyanil), glyoxal-bis-(4-dimethylaminoanil), biacetyl-bis-(4-dimethylaminoanil), glyoxal-bis-(2,6- dimethyl-4-ethoxyanil biacetyl-bis-( 2,6-dimethyl-4- ethoxyanil), Z-pyridine carboxyaldehyde anil, 2- pyridine carboxaldehyde-Z-methylanil, 2-pyridine carboxaldehyde-4-methylani1, 2-pyridine carboxaldehyde-Z-isopropylanil, Z-pyridine carboxa1dehyde2- ethylanil, Z-pyridine carboxa1dehyde-4methoxyani1, Z-pyridine carboxaldehyde-4dimethylaminoanil, 2- pyridine carboxaldehyde-2,6-dimethyl-4-methoxyani1, Z-pyridine carboxaldehyde-Z,6-dimethyl-4- dimethylaminoanil, Z-pyridine carboxaldehyde-Zbdiethyl-4-diethylaminoanil, 2-acetylpyridine-2- methylanil. 2-acetylpyridinel-methylanil, 2- acetylpyridine-Z-isopropylanil. 2-acetylpyridine-2,6- diethylanil, Z-acetylpyridine-4-mcthoxyanil, Zacetylpyridine-4-dimethylaminoanil, 2-acetylpyridinc-2,6- dimethyl-4-mcthoxyanil, 2acetylpyridine-2,o-diethyl- 4-aminoanil, 2,2'-bipyridyl. (w-methyl-ZQ-bipyridyl 5,5-ditert butyl-2,2-pyridyl, 4,4-dimethoxybipyridyl, 4,4-di-(di-methylamino)bipyridyl.

The components of the catalyst system employed in this invention should be pure as can be economically obtained and the catalyst components as well as the codimerization reaction system should be essentially free of moisture and other deleterious substances. The iron compound and the ligand should be mixed together before the reducing agent is added.

In the particular catalyst system of this invention cyclopentadiene is a poison that is significently detrimental to the activity if it is above 200 parts per million. Other hydrocarbons such alkanes, olefins and alkynes are not detrimental to this system. Therefore, an aspect of this invention is that an isoprene monomer stream does not have to be high purity. For example, an isoprene monomer stream containing about 28 percent isoprene (contaminated with alkanes, alkenes, and about one percent of acetylenic compounds) can be effectively used for codimerization with the catalysts described in the present invention.

The mole ratios of the reactants can vary over a considerable range. For instance, the mole ratio of the iron compound to the mole ratio of the conjugated diolefin can range from about 10/1 to about 10 /1; however, a more preferable range is from about 1000/1 to about 10 1.

The mole ratio of the ligand to the iron compound may vary from about 0.7/1 to about 5/1. A more preferred range would be from about l/l to about 3/1.

The mole ratio of the reducing compound to the iron compound may range from about 1/1 to about 12/1. A more preferred range is from about 4/1 to about 9/1.

The temperature at which the codimerization process of this invention is conducted may vary from a low temperature of about 60C. up to 130C. However, it has been found that the best results have been obtained when the reaction is run from about to about C. The reaction may be run as a batch or continuous process. The diolefin may be added to the reaction mixture all at once, or gradually. It is usually desirable, but not necessary, to conduct the codimerization in the presence of an inert solvent or diluent. The term inert" is meant to denote that the solvent has no adverse effect on the reaction. Representative of such solvents are pentane, hexane, heptane, octane, cyclohexane, mixtures of petroleums boiling between 60C. and 200C, benzene, toluene, ethylbenzene, xylene, 1,5- cyclooctadiene, dimethyl-1,5cyc1ooctadiene or mixtures thereof. When diethyl aluminum ethoxide is used as a reductant, diethyl ether or anisole may be used as solvent.

The pressures which are employed in this process can range from ambient pressure created by the monomer/- solvent system at operating temperature up to 5000 psig. Preferably, however, it is practical to employ pressures from about 200 to 1000 psig with reactions involving ethylene, and 50-600 psig with propylene or l-butene. reactions.

Further practice of this invention is illustrated by reference to the following examples which are intended to be illustrative and in no manner limiting.

EXAMPLE 1 To a 100 ml. reactor under an ethylene atmosphere was added iron octanoate (0.05 millimolcs in mineral spirits), 13.2 mg of glyoxal-bis-2,6-dimethylanil in 10 ml. isoprene (containing pentane as an internal standard), and 0.2 millimolcs of triethylaluminum (Et Al) in 4.85 ml. of xylene. The reactor was pressurized with ethylene to 600 psi, and the reaction mixture was stirred at 90C. for 30 minutes. A 3 ml. sample of the reaction mixture was quenched in a mixture of 30 ml. of chlorobenzene and 0.2 ml. of H 0, then analyzed by gas chromatography. lsoprene conversion was 90 percent. Selectivities to 4- and 5-methyl-1,4-hexadienes were 67 and 28 percent, respectively. By-products were formed in 5 percent selectivity.

EXAMPLE II The same procedure was used as in Example 1 except that the ligand was not added to the catalyst system. lsoprene conversion was 35 percent. Selectivities to 4- and 5-methyl-1,4-hexadienes were 34 and 36 percent respectively. By-products were formed in 6 percent Selectivity and isoprene dimers were formed in 24 per cent selectivity.

EXAMPLE III This comparative example illustrates how a ligand which does not contain the -N=CC=N moiety affects the conversion and desired selectivity. The following run was made: 0.05 millimoles of iron octanoate, l 17 milligrams of ethylene bisbenzilidine in 15 milliliters of xylene and 15 milliliters of isoprene (containing pentane as an internal standard) were put in a 100 milliliter reactor at 90C. under 100 psig of ethylene. The mixture was treated with 0.1 milliliters of 2 molar Et Al, and shaken under 600 psig of ethylene at 90C. for 30 minutes. lsoprene conversion was 42 percent. Selectivity to 4-methyl-l.4-hexadiene was 31 percent. Selectivity to 5-methyl-1.4-hexadiene was 34 percent. Selectivity to by-products was 6 percent.

EXAMPLE IV To a 100 ml. reactor was added 0.05 millimoles of iron octanoate, 16.2 milligrams of biacetyl-bis(4- ethoxyanil) in 10 milliliters of toluene, and milliliters of isoprene (containing pentane as an internal standard) at 90C. (under 100 psig of ethylene). The mixture was treated with 0.1 milliliters of 2 molar Et- ;,Al. and shaken under 600 psig of ethylene at 90C. for 30 minutes. lsoprene conversion was 100 percent. Selectivity to 4-methyl-l ,4-hexadiene was 39 percent. Selectivity to 5-methyl-1,4-hexadiene was 47 percent.

EXAMPLE V Example V is similar to Example IV except that 7.7 milligrams of 2.2-bipyridyl were used as the ligand. lsoprene conversion was 99.7 percent. Selectivity to 4-methy1-l,4-hexadiene was 30 percent. Selectivity to 5-methyl-1,4-hexadiene was 40 percent.

EXAMPLE VI To a 100 ml. reactor under an ethylene atmosphere was added iron octanoate (O. 15 millimoles), 23.1 milligrams of 2,2bipyridyl in 10 milliliters of toluene, 15 milliliters of isoprene, 0.6 millimoles of Et;,Al in 0.3 milliliters of toluene at 90C. The reactor was pressurized with ethylene at 900 psig. and stirred at 90C. for 10 minutes. lsoprene conversion was 99 percent. Selectivity to 4-methyl-l .4-hexadiene was 30 percent. Selectivity to S-methyl-l .4-hexadienc was 43 percent.

EXAMPLE V11 Example VII is similar to Example VI except that 46.2 milligrams of 2,2-bipyridyl was used. lsoprene conversion was 91 percent. Selectivities to 4- and 5-methyl-l,4-hexadiene were 30 and 43 percent respectively.

EXAMPLE VIII EXAMPLE IX To a 30 ml. reactor was added 5 gms. propylene, 2.8 ml. of xylene, 0.1 millimoles of iron octanoate, 26.4 mg. of glyoxal-bis-2,6-dimethylanil in 1 ml. of xylene, 5 ml. of isoprene, 0.4 millimioles of Et Al in 1.2 m1. of xylene and then shaken at 100C. for minutes. lsoprene conversion was 13 percent. Two C unconjugated dienes were formed in 54 and 34 percent selectivity, respectively.

EXAMPLE X To a 100 ml. reactor was added iron octanoate (0. l 5 millimoles in mineral spirits), 39.6 milligrams of g1yoxalbis-2.6-dimethylanil in 10 milliliters of xylene, l5 milliliters of isoprene 0.6 millimoles of Et -,Al in 4.5 milliliters of xylene. Procedures similar to Example I were used. lsoprene conversion was 100 percent. Selectivities to 4' and 5-methyl l ,4-hexadienes were and 8 percent respectively. No isoprene dimers were observed.

EXAMPLE XI To a 30 ml. reactor under an ethylene atmosphere was added iron octanoate (0.05 millimoles), 0.075 mil limoles of biacetyl bisanil in 2.55 milliliters of xylene, 5 milliliters of isoprene (96.5 percent pure), 0.2 millimoles of Et Al in 2.4 milliliters of xylene at C, then treated with 100 milliliterss of ethylene and shaken at 100C. for 1 hour. The reaction mixture was analyzed as in Example I. lsoprene conversion was 99 percent. Selectivities t0 4- and S-methyll ,4-hexadiene were 43 and 37 percent, respectively.

EXAMPLE XII To a 100 ml. reactor under an ethylene atmosphere was added iron octanoate (O. 15 millimoles), 35.4 millimoles of glyoxal-bis (2-methy1anil) in 10 milliliters of toluene, l5 milliliters of isoprene, 0.6 millimoles of EtgAl in 0.3 milliliters of toluene at 90C. The reactor was pressurized with ethylene at 600 psig, and stirred for 30 minutes. lsoprene conversion was 99.7 percent. Selectivity to 4-methy11,4-hexadiene was 40 percent. Selectivity to 5-methy1-1,4hexadiene was 40 percent.

EXAMPLE XIII To a 100 ml. reactor under an ethylene atniififil lel was added iron octanoate (0.15 millimoles), 3 i=5 Ynilligrams of pyridine-Z-carboxaldehyde-Z-methylilflil in 45 milliliters of toluene, 0.6 millimoles of Et Al in (1.3 milliliters of toluene at 90C. The reactor was BIsuri2ed with ethylene at 600 psig, and stirred for Ininutes.

lsoprene conversion was 93 percent. Selectivities to 4- and 5-mcthyl-l,4-hexadiene were 35 percent and 42 percent respectively.

EXAMPLE XIV EXAMPLE XV A similar procedure was used as in Example XIV except that 312 milligrams of 2,2-bipyridyl was used as the ligand. lsoprene conversion was 70 percent. Selectivity to 5-methyl-l ,4-hexadiene was 50 percent. Selectivity to 4-methyl-l,4-hexadiene was 31 percent.

The catalyst system of the present invention can be used to recover butadiene values from C streams and isoprene and piperylene values from C streams by mixing the stream with ethylene and the catalyst, forming a codimer, and separating the stream from the codimer by fractional distillation.

EXAMPLE XVI In a l-liter stainless steel reactor were charged 30 milliliters of xylene, and 100 milliliters of a (sodium distilled) C by-product stream (containing 7 percent C C alkanes, 65 percent C olefins, 28 percent isoprene, and traces of acetylenes, dimethylsulfide, diethylether, and l,5cyclopentadiene). The mixture was heated to 90C. under 200 psig of ethylene, treated with a mixture of 0.5 millimoles of iron octanoate, 320 milligrams of biacetyl-bis(4-ethoxyanil), and 3 millimoles of triethylaluminum in milliliters of xylene, and stirred under 600 psig of ethylene for 30 minutes.

lsoprene conversion was 99.7 percent. Selectivity to 5-methyl-l,4-hexadiene was 60 percent. Selectivity to 4-methyl-l,4-hexadiene was percent.

EXAMPLE XVll In a l-liter stainless steel reactor were charged 30 milliliters of xylene, and 100 milliliters of a (sodium distilled) C,-, by-product stream (containing 6 percent C -C alkanes, 46 percent C olefins, 22 percent isoprene, 26 percent trans-piperylene, and traces of acetylenes, dimethylsulfide, diethylether, and 1,5- cyclopentadiene). The mixture was heated to 90C.

under 200 psig of ethylene, treated with a mixture of i 0.5 millimoles of iron octanoate, 320 milligrams of biacetyl-bis(4-ethoxyanil) and 3 millimoles of triethylaluminum in 20 milliliters of xylene. and stirred under 600 psig of ethylene for 20 minutes. lsoprene conversion was 98.6 percent, and selectivities to 5- and 4methyl-l,4-hexadiene were 54 and 36 percent respectivelyv Piperylcne conversion was 97.4 percent and selectivities to 3-methyl-l,4-hexadiene and 1,4 heptadiene were 87 and 5 percent respectively.

While certain representative embodiments and details have been shown for the purpose ofillustrating the invention. it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

l. A process for codimerizing conjugated diolefins selected from the group consisting of isoprene, piperylene, Z-ethyll ,3-butadiene, 2-phenyl-l ,3-butadiene, 2-methyl-l ,3-pentadiene and 3-methyll ,3-pentadiene with lower a-olefins to nonconjugated diolefins which comprises contacting said diolefins and lower a-olefins with a ternary catalyst system consisting essentially of l an iron compound selected from the group consisting of iron salts of carboxylic acids containing from 2 to 40 carbon atoms and iron complexes of 1,3- diketones, (2) an organoaluminum compound selected from the group consisting of trialkyl aluminurns, lithium tetraethyl aluminate and diethyl aluminum ethoxide, and (3) a bidentate nitrogen compound selected from the group consisting of glyoxal-bis(2,6- dimethylanil), biacetyl-bis-(2,6-dimethylanil), glyoxalbis-(4-methylanil), biacetyl-bis'(4-methylanil), glyoxal-bis-( Z-methylanil biacetyl-bis-( 2-methylanil glyoxal-bisanil, biacetyl-bisanil, glyoxal-bis-(4- ethoxyanil), biacetyl-bis-(4-ethoxyanil glyoxal-bis-( 3- methoxyanil biacetyl-bis-( 3-methoxyanil glyoxalbis-( 4-dimethylaminoanil biacetyl-bis-( 4- dimethylaminoanil glyoxal-bis-( 2,6-dimethyl-4- ethoxyanil), biacetyl-bis-( 2,6-dimethyl-4-ethoxyanil 2-pyridine carboxaldehydeanil, Z-pyridine carboxaldehyde-Z-methylanil, 2-pyridinecarboxaldehyde-4 methylanil, Z-pyridinecarboxaldehyde-Z-isopropylanil, 2-pyridinecarboxaldehyde-Z-ethylanil, 2- pydridinecarboxaldehyde-4-methoxyanil, 2- pyridinecarboxaldehyde-4-dimethylaminoanil, 2- pyridinecarboxaldehyde-2,6-dimethyl-4-methoxyanil, Z-pyridinecarboxaldehyde-2,6-dimethyl-4- dimethylaminoanil, Z-pyridinecarboxaldehyde-2,6- diethyl-4-diethylaminoanil, 2-acetylpyridine-2- methylanil, 2-acetylpyridine-4-methylanil, 2- acetylpyridine-2-isopropylanil, 2-acetylpyridine-2,6- diethylanil, 2acetylpyridine-4-methoxyanil, 2- acetylpyridine-4-dimethylaminoanil, 2-acetylpyridine- 2,6-dimethyl-4methoxyanil and 2-acetylpyridine-2,6- diethyl-4diethylaminoanil.

2. A process according to claim 1 wherein the lower a-olefin is ethylene and has a pressure of from 200 to 1000 psig; the mole ratio of the iron compound/conjugated diolefin is lOOO/l to 10 /1; the mole ratio of the bidentate nitrogen compound/iron compound is from 1/1 to 3/1; the mole ratio of the organoaluminum compound/iron compound is rom 4/1 to 9/1, and the organoaluminum compound is a trialkyl aluminum.

3. A process according to claim 1 wherein the lower a-olefin hydrocarbon is selected from the group consisting of ethylene, propylene and l-butene.

4. A process according to claim 3 in which isoprene and ethylene are codimerized, wherein the catalyst consists of glyoxal-bis2,6-dimethylanil, iron octanoate and triethyl aluminum whereby said hydrocarbons are converted to 4 and 5-methyl-l,4-hexadienes, whereby the 4-methyl-l,4-hexadiene is the major product.

5. A process according to claim 3 in which isoprene and ethylene are codimerized wherein the catalysts consist of iron octanoate, biacetyl-bis-4- dimethylaminoanil and triethylaluminum, whereby said hydrocarbons are converted predominately to S-methyll ,4-hexadiene.

6. A process according to claim 3 in which isoprene and ethylene are codimerized wherein the catalysts consist of iron octanoate, biacetyl-bis-3,4-diethoxyanil and triethylaluminum whereby said hydrocarbons are converted to predominately 5-methyl-l,4hexadiene. 

1. A PROCESS FOR CODIMERIZING CONJUGATED DIOLEFINS SELECTED FROM THE GROUP CONSISTING OF ISOPRENE PIPERYLENE 2-ETHYL-1,3BUTADIENE 2-PHENYL-1,3-BUTADIENE 2-METHYL- 1,3-PENTADIENE AND 3-METHYL 1 3-PENTADIENE WITH LOWER A-OLEFINS TO NONCONJUGATED DIOLEFINS WHICH COMPRISES CONTACTING SAID DIOLEFINS AND LOWER A-OLEFINS WITH A TERNARY CATALYST SYSTEM CONSISTING ESSENTIALLY OF (1) AN IRON COMPOUND SELECTED FROM THE GROUP CONSISTING OF IRON SALTS OF CARBOXYLIC ACIDS CONTAINING FROM 2 TO 40 CARBON ATOMS AND IRON COMPLEXES OF 1,3-DIKETONES (2) AN ORGANOALUMINUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRIALKY ALUMINUMS LITHIUM TETRATHYL ALIMINATE AND DIETHYL ALUMINUM ETHOXIDE AND (3) A BIDENTATE NITROGEN COMPOUND SELECTED FROM THE GROUP CONSISTING OF YOXAL-BIS-72,6DIMETHYLANIL), BIACETYL-BIS-(2,6-DIMETHYLANIL) GLOXAL-BIS-(4METHYLANIL) BIACETYL-BIS-(4-METHYLANIL) GLYOXAL-BIS-(2METHYLANIL) BIACETYL-BIS(2-METHYLANIL , GLOXAL-BISMANIL BIACETYL-BISANIL GLYOXAL-BIS-(4-ETHOXYANIL) BIACETYL-BIS-4ETHOXYANIL), GLYOXAL-BIS-(3-METHOXYANIL) BIACETYL-BIS-3METHOXYANIL), GLYOXAL-BIS-(DIMETHYLAMINOANIL) BIACETYLBIS-(J-DIMETHYLAMINOANIL) GLYOXAL-BIS-(2,6-DIMETHYL-4-ETHOXYANIL), BIACETYL-BIS-(2,6-DIMETHYL-4-ETHOXYANIL), 2-PYRIDINE CARBOXYALEDEHYDEANIL 2-PYRIDINE CARBOXYALDEHYDE 2-METHYLANIL 2-PYRIDINECARBOXALDEHYDE-4-METHYLANIL 2-PYRIDINECARBOXYBOX ALDEHYDE-2-ISOPROPYLANIL 2-PYRIDINECABOXALDEHYDE-2ETHYLANIL 2-PYDRIDINECARBOXYLDEHYDE-4-METHOXYANIL 2PYRIDINECARBOXALDEHYDE-4-DIMETHYLAMINOANIL 2-PYRIDINECARBOXALDEHYDE 2,6-DIMETHYL-4-METHOXYANIL 2-PYRIDINECARBOXALDEHYDE 2,6-DIMETHYL-4-DIMETHYLAMINOANIL 2-PYRIDINECARBOXALDEHYDE 2,6-DIETHYL-4-DIETHYLAMINOANIL, 2-ACETYLPYRIDINE-2-METHYLANIL 2-ACETYLPYRIDINE-4-METHYLLANIL 2-ACETYLPYRIDINE-2-ISOPROPYLANIL 2-ACETYLPYRIDINE 2,6-DIETHYLLANIL, 2-ACETYLPYRIDINE-4-METHOXYANIL 2-ACETYLPYRIDINE-4/DIMETHYLAMINOANIL 2-ACETYLPYRIDINE 2,6-DIMETHYL-4-METHOXYANIL AND 2ACETYLPYRIDINE 2,6-DIETHYL-4-DIETHYLAMINOANIL.
 2. A process according to claim 1 wherein the lower Alpha -olefin is ethylene and has a pressure of from 200 to 1000 psig; the mole ratio oF the iron compound/conjugated diolefin is 1000/1 to 104/1; the mole ratio of the bidentate nitrogen compound/iron compound is from 1/1 to 3/1; the mole ratio of the organoaluminum compound/iron compound is from 4/1 to 9/1, and the organoaluminum compound is a trialkyl aluminum.
 3. A process according to claim 1 wherein the lower Alpha -olefin hydrocarbon is selected from the group consisting of ethylene, propylene and 1-butene.
 4. A process according to claim 3 in which isoprene and ethylene are codimerized, wherein the catalyst consists of glyoxal-bis-2, 6-dimethylanil, iron octanoate and triethyl aluminum whereby said hydrocarbons are converted to 4 and 5-methyl-1,4-hexadienes, whereby the 4-methyl-1,4-hexadiene is the major product.
 5. A process according to claim 3 in which isoprene and ethylene are codimerized wherein the catalysts consist of iron octanoate, biacetyl-bis-4-dimethylaminoanil and triethylaluminum, whereby said hydrocarbons are converted predominately to 5-methyl-1,4-hexadiene.
 6. A process according to claim 3 in which isoprene and ethylene are codimerized wherein the catalysts consist of iron octanoate, biacetyl-bis-3,4-diethoxyanil and triethylaluminum whereby said hydrocarbons are converted to predominately 5-methyl-1,4-hexadiene. 